Introduction

Thanks to advances in modern medicine and technology the outcome of preterm infants has improved dramatically. Many infants are now surviving who are born as young as 23 weeks' gestation and as small as 450 g. These infants enter life with their maternal nutrient supply abruptly disconnected and with only minimal nutrient stores. There is no other time in the life cycle when nutrition is more crucial. Additionally, nutrition in this early neonatal period may have an impact upon health throughout life.

These infants are vulnerable to poor growth and abnormal developmental outcome if not nourished appropriately. Since the preterm infant lacks the ability to voluntarily consume and process nutrients, all of the infant's needs must be provided through enteral and frequently parenteral nutrition. Preterm infants have numerous nutritional risk factors. Nutrient stores are accumulated during the third trimester; therefore, preterm infants have low energy reserves as well as minimal reserves of other nutrients. In fact, infants with birth weights less than 1000 g have energy reserves of less than 200kcalkg-1 (836kJkg-1). The metabolic rate of the preterm infant is elevated due to the predominance of metabolically active tissue and minimal fat stores. Protein, fat, and glucose needs are very high to provide adequate energy for metabolism, fat deposition, and growth. The preterm infant has excessive evaporative losses and increased urinary losses, which greatly increase fluid needs. The gastrointestinal tract of the preterm infant is very immature with minimal production of enzymes and growth factors, poor gastric emptying, and discoor-dinated peristalsis. To further complicate the provision of nutrients, preterm infants have episodes of metabolic instability including hypo- and hypergly-cemia, poor lipid clearance, and electrolyte disturbances. The preterm infant also has high rates of stressful events including respiratory distress, hypox-emia, hypercarbia, and sepsis.

Usually, the goal is to provide sufficient nutrients to achieve the fetal growth rate. However, since the fetus and newborn differ in both physiology and metabolism this may not be an appropriate goal and in actuality this goal is rarely achieved both in regards to growth as well as body composition.

Most preterm and low-birth-weight infants show significant delays in growth due to the inability to provide adequate nutrients especially in the first few weeks following birth. Over the past several years, improvements in neonatal management and a more aggressive approach to nutrition have accelerated growth but it still lags behind the fetal growth rate. However, the growth potential of preterm infants may actually be greater than even that of the normal infant. Growth velocity in the infant is greatest between 25 and 30 weeks' gestation, greater than at 40 weeks. If the infant is undernourished during this key growth period, adequate catch-up growth may never be achieved. Protein and energy are the key nutrients for growth, but they must be provided in appropriate proportions for the optimal utilization of both. Vitamins, minerals, and electrolytes must also be supplied in adequate amounts and proportions to contribute to growth. During the first few weeks after birth most preterm infants are usually undernourished due to instability so that once stability is achieved an increased supply of nutrients may be necessary to achieve catch-up growth. Nutrients are usually supplied parenterally in the initial period, gradually transitioned to a combination of parenteral and enteral nutrition, and finally when stability has been achieved full enteral nutrition.

How To Reduce Acne Scarring

How To Reduce Acne Scarring

Acne is a name that is famous in its own right, but for all of the wrong reasons. Most teenagers know, and dread, the very word, as it so prevalently wrecks havoc on their faces throughout their adolescent years.

Get My Free Ebook


Post a comment